A novel synthesis method of carbon-coated LiNil/3Mnl/3COl/302 cathode material for lithium-ion battery was reported. The carbon coating was produced from a precursor, glucose, by microwave-pyrolysis method. The prepared powders were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, X-ray fluorescence （XRF） and charge/discharge tests. XRD results indicate that the carbon coating does not change the phase structure of LiNil/3Mnl/3C01/302 material. SEM results show that the surface of spherical carbon-coated material becomes rough. Electrochemical performance results show that the carbon coating can improve the cycling performance of LiNii/3Mnl/3C01/302. The specific discharge capacity retention of the carbon-coated LiNi1/3Mnt/3Col/30z reached 85.0%-96.0% at the 50th cycle at 0.2C rate, and the specific discharge capacity retention is improved at a high rate.
Aluminum phosphate(AlPO_(4))was used to modify the surface of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM)cathode material.The surface structure and electrochemical properties of the coated materials were investigated by X-ray photoelectron spectroscopy(XPS)and electrochemical impedance spectroscopy(EIS).The results confirm the formation of aluminum-containing solid solution on the surface of NCM particles.An aluminum phosphate coating blocks the Li+insertion-extraction process in cells charged at high rates at room temperature,increasing surface film resistance and decreasing discharge capacity.However,an aluminum phosphate aids the formation of a stable solid electrolyte interface film on NCM surface and stabilizes the Rct of cell as samples electrochemically cycled at 55℃.The electrochemical studies suggest that the initial columbic efficiency is significantly enhanced.An NCM sample coated with 1.0 wt%AlPO_(4) delivers a higher discharge capacity and shows excellent capacity retention ability.
Jian-Hua WangYu WangYu-Zhong GuoChang-Wei LiuLu-Lu Dan
